1. Field of Invention
This invention relates to the medical treatment of diseased nails, claws or hoofs (i.e., unguis), and specifically relates to the treatment of diseased nails by facilitating penetration of medication through the nail.
2. Statement of the Art
Humans and animals alike are commonly plagued by the infiltration of micro-organisms beneath the nail, claw or hoof which results in a disease condition causing pain, discoloration, and frequently loss of the unguis. In humans, for example, some diseases which attack the nail or nail bed can be treated fairly successfully with the use of cleansing and/or antiseptic preparations, while other diseases require treatment by such means as systemic drug therapy. Nonetheless, many disease conditions of the nail, particularly onychomycosis (i.e., fungal diseases), have had a relatively low success rate for treatment due to the intransigent nature of the infectious micro-organisms.
It has been estimated that greater than twenty percent (20%) of the population of the United States over the age of 40 suffers from onychomycosis of the fingernails or toenails. The disease is known to occur to a lesser extent in people below the age of forty, but the occurrence of disease is still significant. Unfortunately, the current modalities for treatment of onychomycosis show a very low success rate.
Common means of treating microbial diseases, including onychomycosis, include oral administration of drugs and laser therapy. Laser therapy, as yet, is not well-developed nor widely practiced, and is very expensive because it must be conducted in a doctor's office by a trained technician. Systemic drug therapy through oral administration has also proven to be relatively unsuccessful because of drug intolerances, the expense of the medications and low patient compliance.
The most common means of treating onychomycosis is to remove the nail completely and topically apply medication to the underlying nail bed. However, not only is such treatment cosmetically unsightly, but the fungus which invades the nail often remains in the matrix of the finger or toe (where the nail is formed) and the disease reoccurs immediately upon, or during, ingrowth of the new nail.
Undoubtedly, treatment of diseases involving nails would be greatly enhanced by the ability to access the area around and below the nail, as well as to penetrate the nail itself, without having to remove the nail. However, the thick and/or hardened nature of nails renders access through, and to the area below, the nail very difficult. The same can be said of diseases involving the claws or hooves of animals.
The usefulness of antifungal drugs in treating onychomycosis has been limited heretofore because of resistance to penetration of the nail or because of limited access to the nail bed through the nail. Thus, it would be an improvement in the art to provide means for enhancing penetration of the nail so that treatment of the nail with medication may occur at the situs and without having to remove or otherwise significantly damage the nail. It would also be advantageous to provide such penetration means at a reasonable cost to the consumer, and in a form which would facilitate and encourage proper and consistent self-use by the afflicted person.
The art has disclosed the use of various substances as permeation facilitators in drug delivery systems, but such permeation enhancers have only been used in connection with permeation of the epidermis. Examples of such methods and systems have been disclosed in U.S. Pat. No. 5,156,846; U.S. Pat. No. 5,296,222; French Patent Publication No. 2,448,903; and French Patent Publication No. 2,556,218. The permeation of thickened nails, or other unguis, presents unique difficulties not encountered in permeation of the epidermis. To date, no means have been developed to enhance permeation of nails for effective treatment of diseases involving nails, or other unguis.